The bearing structure of, for example, a lever type hoist/traction apparatus, as shown in FIG. 6, is so constructed that a tubular shaft T having a load sheave is supported between a pair of side plates. Outside one side plate A a reduction gear mechanism D is disposed comprising a driving shaft S1, intermediate shafts S2, and reduction gears including a first gear G1, two second gears G2, two third gears G3, and a fourth gear G4 so as to transmit a rotary driving force of an operating lever, while being decelerated by the reduction gear mechanism D, from the tubular shaft T toward the load sheave. On the side plate A a gear cover C is mounted for covering the entire reduction gear mechanism D; and driving shaft S1 and intermediate shafts S2 are supported at one axial ends thereof to gear cover C. For supporting the driving shaft S1 and intermediate shafts S2 to the gear cover C, through-bores a and b are formed at the support portions of the shafts S1 and S2, and the axial ends of the shaft are supported in the through-bores a, b and c through bearings B1 and B2. However, in the above-mentioned support means, since the through-bores a, b and c are formed at the support portions of the shafts S1 and S2 the gear cover C respectively, a foreign objects such as water or sand, may enter into the interior from the through-bore a, b or c; or an external object may hit the bearing B1 or B2, whereby the bearing B1 or B2 may shift in position by the external force. Accordingly, a closing member H for closing the through-bores a, b and c is usually mounted to the outside of gear cover C, thereby preventing foreign objects from entering into the gear cover or the bearing B1 or B2 from shifting. In addition, in FIG. 6, the reduction gear mechanism D uses the driving shaft S1 and two intermediate shafts S2 disposed in parallel thereto, the first gear G1 is supported on the driving shaft S1, the fourth gear G4 is supported on the tubular shaft T coaxial with the driving shaft S1, and the two second gears G2, engageable with the first gear G1, and the two third gears G3, engageable with the fourth gear G4, are supported onto the intermediate shafts S2 respectively, so that the rotary driving force from the operating lever is decelerated by the gears G1, G2, G3 and G4 respectively, whereby the decelerated rotary driving force is adapted to be transmitted toward the load sheave from the fourth gear G4 through the tubular shaft T.
In the bearing structure for the above-mentioned lever type hoist/traction apparatus, in order to close the through-bores a, b and c for supporting one axial ends of the driving shaft S1 and one axial ends of intermediate shafts S2 respectively, it is required to separately mount the closing member H to the gear cover C. Hence, not only the number of parts increases, but also labor of machining the through bores a, b, and c at the gear cover C and the work of fixing the bearings B1 and B2 to the through-bores a, b and c and of mounting the closing member H to the gear cover c are extremely complicated, thereby creating the problem that necessary working efficiency is inferior and working time is quite large. Moreover, the gear cover C is subjected to a large load torque following rotation of the driving shaft S1 or each intermediate shaft S2. When the through-bores a, b and c are formed at such gear cover C, a large load torque locally acts on the portion of the respective through-bores a, b and c, such that there is a chance that these parts will be deformed. Accordingly, it is required to increase the thickness of the gear cover C to separately attach a reinforcing plate thereto for reinforcing the gear cover C.